The use of catheters in guiding, diagnostic, therapeutic, and other interventional procedures is known. One commonly used type of catheter is the intravascular catheter employed for the treatment of cardiovascular disease. An even more specific type of catheter is that which is employed in percutaneous translumenal coronary angioplasty (PTCA). PTCA procedures have gained wide acceptance in recent years as efficient and effective methods for treating types of vascular disease and are commonly used for opening stenoses in the coronary arteries and are used for treating stenoses in other vascular regions as well.
PTCA is well known in the art and typically involves the use of a guide catheter, a guide wire and a balloon catheter, possibly in combination with other intravascular devices. A typical balloon catheter has an elongate shaft with a balloon attached proximate its distal end and an inflation manifold attached proximate the proximal end. In use, the balloon catheter is advanced through a lumen in the guide catheter over the guide wire such that the balloon is positioned adjacent a restriction in a diseased vessel. The balloon is then inflated and the restriction in the vessel is opened.
Current PTCA catheters also often have a short strain relief surrounding a hypotube segment or other polymeric shafts having one or more lumens that form the proximal shaft of the catheter. Hypotubes, or thin-walled polymeric tubing used for catheter shafts, can kink if bent too sharply. Strain reliefs are commonly formed of a polymeric material extending distally from a manifold affixed to the proximal end of a catheter shaft. The current designs can inhibit kinking where the hypotube or polymeric tube exits the manifold within the strain relief.
Guiding catheters are generally comprised of a shaft which is hollow, defining an inner lumen. The shaft is generally comprised of two tubes congruent to each other with a support member therebetween. A hub is connected to the proximal end of the shaft to provide a means for connecting another device such as a syringe to inject fluids, or for providing a means to direct the device in order to place it within the vessel. A tip of a desired shape is provided at the distal end of the shaft.
Furthermore, due to the fact that catheters are maneuvered through very small body lumen, they have specific flexibility requirements that vary with the location along the catheter length. Less flexibility may be required in the catheter proximal portion, where the catheter may lie within a large inside diameter, straight vessel portion. Greater flexibility is often a design goal in the catheter distal portion, where traversing small inside diameter, tortuous vessels may be required. In the catheter mid-region, a gradually, distally increasing flexibility is desirable rather than an abrupt change from low to high flexibility.
Thus, catheter construction often involves various sections which are formed from different polymeric materials depending on the physical requirements of the particular section. For example, catheter construction may involve the formation of an inner shaft with a relatively low melting temperature polymeric material and formation of the manifold with a relatively higher melting temperature polymeric material.
However, molding two such different polymeric materials together can be difficult due to the differences in melting temperature of the materials employed in making the various catheter components. Relatively lower melting temperature polymeric materials may be employed in formation of an inner shaft, for example, while a manifold may be formed from a relatively higher melting temperature polymeric material which, if molded over the inner shaft, can result in deformation of the inner shaft at the temperatures required for processing the relatively higher melting temperature polymeric material to form the manifold. This may lead to defective parts. Consequently, the manifold and the inner shaft are typically molded separately and then later secured together using standard techniques such as adhesive bonding or through welding if possible. Obviously, this requires more steps and less efficiency in the manufacturing process. This is only one example of how various components of a catheter device may be manufactured and assembled.
Thus, there remains a need in the art for a more efficient way to manufacture such catheter devices, as well as improved catheter devices themselves which meet the flexibility and other performance characteristics required.